Means for casting metals, including their alloys.



C. VICKI-IRS.

MEANS FOR CASTING METALS, INCLUDING THEIR ALLOYS.

APPLICATION FILED AUG-29,1914.

1,172,506. Patented Feb. 22, 1916.

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wzm 2 M men smarts PATENT QJFFJIQE,

CEARLES VICKERS, OF NIAGARA FALLS, NEW YORK, ASSIGNOB TO THE TITANIUM ALLQY MANUFACTURING COMPANY, OF NEW YORK, N. Y., A CORPORATION OF MAINE.

a vance,

To all whom it may concern:

Be it known that 1, CHARLES VIcKnns, a subject of the King of Great Britain, and a resident of Niagara Falls, in the county of, Niagara and State of New York, have invented certain new and useful Improvements in Means for Casting Metals. ln-- eluding Their Alloys, of which the following is a specification.

My present invention relates to the casting of metals, and, particularly, of certain of their alloys, and its objects comprise provision of a method whereby, by aid of the novel means herein described and claimed, the tensile strength, ductility, homogeneity, purity, and other desirable properties, of the resulting castings may be enhanced in a manner more simple, economical, and certain than heretofore known or practised for such purposes.

It seems now established that the characteristics ofmetals, and especially of certain alloys thereof, may be, more or less, and sometimes controllingly, afiected by .socalled heat-treatments, i. 6., applications thereto of various specific temperatures designedly. produced, or maintained, prior to, during, or after, casting. These phenomenaseem'attributable to physical changes, or also chemical reactions between, constituents of the metallic mass, which areinaugurated, or promoted, or hindered, as the case may be, by various specific temperatures, or

their duration, and are often evidenced by resulting variations in gram, sure of crys- .tals, etc, and also, and in alloys more frequently, by formation, or reduction, of divers chemical compounds during the operation. Acceptance of such doctrines has resulted in resort bymanufacturers to many troublesome, expensive, and -more or less inefficient 'expedients, in hopes of thereby satisfactorily creating, adjusting, regulate ing, maintaining,- varying, or controlling, at various times and stages, the temperatures of the metals operated on, such being, for example, attempts to secure certain specific temperatures during pouring, attempts to delay, or otherwise vary, the temperatures during solidification as by pie-heating the molds, or by quenching, in water, the re; leased casting and even afterkits solidifica .tion as by annealing, or heatiyg and slowly Specification of Letters Patent.

cooling it, etc. A good example of'such expedlents and their results is afforded by the subsequent treatment accorded to manganese steel castings, the annealing and quenching of which has great influence on their physical properties, Therefore, in in dustrial practice, good foundry men in casting different metals and their alloys have felt obliged to pay particular attention to,

"the nature of each, to its temperature in the Patented Feb, 22, 19MB;

Application filed August 29, 1914. Serial No. 859,156. 7

scribed quality and characteristics has, in

short, prior to my invention, proved detri mental to the art, because of the numerous factors entering into the protileIm-and the resulting expense of even approximately solving their required proper bearing on each batch of metal treated. The result has been that castings hitherto obtainable in market, including particularly those of alloyed metals, have too often proved undesirably weak, or otherwise imperfect, owing to segregation, porosity, lack of homogeneity, impurities, and other defects attributable, largely, if not entirely, to substantially unavoidable, imperfect, or insufiicient, regulation', or control,'of the temperature factors during their manufacture on industrial scales. v

The object of my present invention comprises provision of a method, and means for its practice, whereby castings of metals, and particularly oftheir more dificultly treated alloys, may .be manufactured under usual industrial conditions, with less expense than heretofore, with less technical skill and attention on the-part of the operators, and with much greater certainty of final products possessing better qualities including, greater purity and homogeneity, less segregation and porosity, and consequent superior ultimate strength, elongation and reduction. I

ll attain myobject by -my hereinafter described method and means for its practice.

' I have discovered that requisite heat,-

treatment, or regulation, of the tempera} tures ofcastings can be, and is, most readily,

economically, certainly, and efiiciently, applied in all cases by merely correspondingly regulating the composition, or constituents,

. ofthe molds, thus confining all heat-treatment to the period, or stage, of therein coola ing. 1 am thereby enabled to dispense with all 'heatings other than requiredto qualify the metal for pouring, and with all quenchings, or coolings, other than administered through the agency of the constituents of the mold. l have also discovered that final products whose temperatures during -pro-.

duction have been thus regulatedly and sufiicientl'y' controlled and varied by aid of no other medium'than that afi orded by appro priately selected, prepared, and proportioned integral constituents of the mold ltself, are in all desirable characteristics vastly, superior to any hitherto known to ,me including those improved as much as possible by any heretofore practised heat treatments either before, during, or after the casting. li have further discovered that my aforesaid system of heat-treating, during the cooling of the metal, in the mold itself, 2 is usually productive "of the best results when applied in a particular manner, 2'. e,

by the use of certain non-metallic, specific,

fsubstances, or mixtures,.as constituents 'of the mold, and by their special dispositions and arrangements ,relatively as hereinafter exampled.

prising two metals, the one'of which is' of high, an d the otherxof relatively low,.melt ing point; a separationjthroughout the cast, ing into .alloys of difiering composition takes place.

further cooling. Thus when freezing or solidification commences, an alloy rich in the metal of the higher melting point and poor in the metaLof the lowermelting point,

will firstseparate as a solid,and this is fol lowed by' the solidification of yarious other alloys containing progressively lessof the v former metal and more of the latter, the last alloy to separate and solidify being roporti onately very rich in the metal-,9 lower melting point, and correspondingly poor in -ingly lacking to each other;

" Those of suchalloys having the highest fusing point solidify-first and theentire mass becomes only gradually solid by.

the other; this being known as the entectic alloy. The 'resultingcasting'is correspondin homogeneity, is not throughout uniform in composition, and is consequently weaker, in spots, than it should be. I havenfound that this liquation, and its injurious efiec'ts on the product are greatly, or altogether, preventable by chilling the metals, While in the-mold, much more rapidly than I believe has hitherto been 'industriallyknown or attempted. Homogeneity in the molten alloy as regards its constituent metals is by present well known practice sufiicientlyi attainable and maintainable up to the time'of its pouring into the mold. It is in the latter that the undesired, noxious liquation' occurs. lit is there that it must, if possible, be obstructed or prevented, and this i accomplish by there contacting the molten casting with the most rapidly heat-conductive, or difiusive, sub- .stance which I have yet found adapted to the purpose, towit, graphitized carbon, and

usually preferably in the form known as artificial graphite.,.'lo this end 1 construct the mold principally of said substance which is also advantageous for the purpose for the additional reasons that it contains substantially no moisture, and no gases \for the molten metal to absorb, all volatile matter having been expelled therefrom by the high temperatures required for its production, as, for example, usually those of the electric furnace. It is also so extremely refractory, and resistant of high temperatures, as to correspondingly impart permanence to the forms composed in whole, or in part,thereof, thus enabling the use of molds containing it to be correspondingly indefinitelyrepeated. T My present invention therefore comprises the. construction of,the molds in such manner 'asto thereby regulate the cooling to normal temperatures of the therein molten n'ietz'il' at such rates as indicated by'its nature andconstituents and the obtaining of the "best resultant castings.

IVily researches have demonstrated that, as a rule, not only prevention of liquation, but also the all-ar0und perfection and exfcellence of the casting is proportional to the rapidity of itspooling, while it remains in sz'zfu in the mold, and that such rapidity, in the highidegree-"required, is best, most practically, and least expensively attainable by the influence, or through the, medium of,

a constituent substance of the mold preferably disposed so as to contact, and thus assist in the'sh'aping of the casting. ;I It is presumable that mere acceleratlon of chill, or solidification, might be imparted by resort to other means or agents, as for ex' ample by auxiliary wateri-coo'ling devices, or an air-blast, but these, in addltlon to other practical-objections, are not only comparatively expensive and difficult of proper application, but they are incapable of producing the same desired influence on, and results in, the metal, as are I obtainable through the rapidity imparted by the high heat-conductive, or diffusive, properties of the molding material itself. Again, al-

though I have found that many substances,

as, for example, metals, and particularly iron, are more rapidly heat-conductive than the sand so generally used in molding; the iron molds hitherto essayed have proved unsatisfactory for many reasons, including their too frequently deleterious effects on the molten metals, their comparative cumbersomeness, the difficulty of producing and manipulating them as required, and especially their incapacity to afiord that relatively accurate and uniform adjustment of the locally, and otherwise varying, heatwithdrawing properties of my molds which is of'importance to the most successful practice of my method.

.I have thus far, as above stated, found no other substance so well adapted to the purposes of my invention as is graphitized carbon. This substance, in addition to its above enumerated favorable qualities, is capable of having its heat-conductive property readily modified and thus adjusted to meet the requirements of different metals, or even different parts of the same casting. For example, I have, to meet some requirements, constructed my ,permanent molds by mixing graphite, either artificial or natural, with any suitable binder such as tar or pitch,- forming it by usual procedures into the proper shape and then baking it in a furnace as in ordinary carbon manufacture. If by this procedure a heat-conductivity is imparted to the mold too great for successful use in certain forms of castings, I have adjusted the heat-conductivity to that reor the polymerization, of the amorphous carbon, and thus correspondingly control the heat conductivity of the resultingmold.

I can also further locally adjust the heatconducting properties of my permanent molds, by varying their thickness at different points, or zones, corresponding with the thicker and thinner parts of the casting,

and, by this means, readily insure more In graphitized carbon mold.

rapid heat wi'thdrawal from the thicker parts, and less rapid from the thinner, thus insuring substantial uniformity of ,heatwithdrawal from all parts of the casting at the same rate and in'equal amount during a glven time.

In cases wherein a permanent mold is not desired or required, I construct a temporary mold such as employed in making many forms of castings. For this purpose if the mold, as rarely if ever happens, is to be composed entirely of graphite, I merely form that substance to the desiredpattern under high pressure, as will readily be understood, and in such instances I have found that the best form of graphite for the purpose is that obtained by the well known decomposition of silicon carbid, or other like carbids, since this form possesses plastic coherent properties when subjected to pressure. Or, as more frequently demanded. I make the temporary mold as last aforesaid, but out of a mixture of graphitized carbon and ordinary molder's sand regulating the proportions so as to impartto the mold the degree of heat-conductivity best suited to the particular kind of casting desired. In such cases I can also. as in the above referred to examples of my per-' manent molds, locally vary and adjust the heat-conductivity of different parts of the mold by correspondingly increasing. or diminishing, the proportion of sand in the mixture at those localities. The comparative merits of my invention have been repeatedly demonstrated.

In one instance, designed particularly to show the influence of my aforesaid methods of rapid cooling on the physical properties of the castings, I employed an alloy containing 92 per cent. of aluminum and 8 percent. of copper. From this alloy I made castings from the same heat in four different molds made respectively of sand, amorphous carbon. iron, and graphitized carbon. Tests of the physical properties of the resulting castings gave the respective results indicated by the subjoined table, viz

Per cent. Per cent. elongatioml reduction.

Ultimate In sand mold 12, 300 In amorphous carbon mold. In iron mold sea-2 Avoaq ecu-coo bon the greatest.

Similar tests made with other alloys gave analogous results. l

Again tests made of the efiiciency of my above referred to temporary molds'made of a mixture of sand with graphite, as Compared with that of sand molds in casting the said alloy of 92 per cent. aluminum and 8 per cent. copper gave the following results Ultimate Per cent. Per cent strength. elongation. reductioxi.

From sand mold 21,650 2. 5' 2.7 From graphite-sand mold 26, 780 4.0 4. 7

l have furthermore discovered that a mold composed entirely of graphitized carbon only is, by itself alone, incompetent to impart, in highest degree, to the castings, the

above noted improved physical characterr, -istics.

My researches have demonstrated that to attain thesemore universally, and perfectly,- than otherwise possible, there is required, in the mold, a combination of the rapidly heat-difi'using substance with anothercomparatively much less so. This, If have discovered, is important for several reasons, as, for example, the need of providing means to overcome the'efi'ects of natural shrinkages and contractions .of the metal, which render it desirable, during solidification, to constantly supply thereto additions thereof, which are,at the time, so

comparatively liquid as to be capable of.

flowing intocavities caused by contractions of the original charge and thus restore thereto its required bulk. Again, as above referred to, some sections of a given cast.-

ing may require more rapid cooling than others, in order that the casting, as a whole,

may solidify at a uniform rate. This, as will be understood, is'the case when a casting consists of alternate thin and heavy sec-. tions, in which event graphitized carbon 1spreferable to form the mold walls around the heavy sections, and some less rapidly heat-difiusing substance such as molding-- sand, amorphous carbon, alundum, alumina, or a mixture thereof as aforesaid with graphitized carbon, is preferable around the thinner sections.

My molds may therefore be made either entirely or, preferably only principally, of the more rapidly heat difiusing substance. In the latter ease, I use that substance as aforesaid,per present methods of constructing a sand-mold, of which it may thus form a part; or, in cases in which my aforesaid combination of substances is relied on to also overcome undesired results of contraction, I employ the less rapidly heat difl using, or conductive, substance as the constituent of the feeder, or riser, portion of the mold proper This riser constitutes a reservoir for metal in excess of that required to first fill the mold, and. is disposed, preferably, so as to communicate With'the highest 1 point of the casting in suchLmanner that such excess ,metal can flow by into the meld to fill the ca ities therein gravity down.

quickly formed by my rapid cooling thereof, or by escape of gases therefrom through the comparatively traversable less solidified' contents of the riser.

For a better understanding of my invention, generally, and as typical of constructions last referred to, I have diagrammatically illustrated my combinationof a more 'sidesof its matrix composed, in this instance, of the more rapidly heat-conducting substance or. mixture, and B is its riser, lined, in the usual manner, with a less rapidly heat-conducting substance, or mixture,

as, for example, ordinary molders sand packed within a bottomless holder B by ramming it therein around a therewith concentric core .(not shown because necessarily withdrawn to produce the cavity for the riser). Bis, as shown, disposed, preferably, on top of the carbon mold and concentrically therewith, and is thus, for the purposes of the operation, a part of the latter,

the'major part of the top-of the matrix of which is,' asshown in'the drawings, covered or inclosed by solid portions of the therewith communicating riser, The mold A is,

in this instance, as is preferable, provided with a therein-contained gate, or duct C, for

charging the molten metal into the mold j proper. This extends, as showmfrom at least the level of the top of the riser to,

preferably, a point C located at the bottom of the matrix of the mold A, though it might vent into the latter at some other -point Into the upper end C of this duct the molten metal is poured. lit is conducted thereby into the mold A in which, and

thence in the risen B, it ascends, in accordance with the laws governing the flow of liquids, until both are charged to the level desired. As soon as the charging has been thus completed that part of the metal designed for the casting proper, D, solidifies rapidly, influenced by the high heat-diffusive substance, or mixture, therewith in' contact, while that portion of the metal located, at E, within the riser, remains relatively molten by reason of its environment by the much less heat-difiusive sand. Therefore,

as the metal in ll) shrinks, that in E sinks into and fills the resulting cavities, thus insuring a more perfect casting than otherwise obtainable' :The beneficial results of this aspect-of my invention are not confined to perfectionment of the products, they'produce also notable economies in the art, particu larly when production of massive castings is involved. This is because much less metal is required to thus pour a casting, fuel, time and labor being correspondingly economized, and also power in the subsequently required mechanical severing from the casting of thethen therewith unitary relatively large body of surplus metal hitherto required for the riser or feeder E. This economy is directly attributable to the comparatively very rapid chilling, per my method, of the metal of the casting proper, its rate being usually many times more rapid than that of the riser. Inasmuch as only relatively small cavities form in D, thus requiring but correspondingly small additional supplies of the metal to fill them, it is, by

my method, possible to successfully employ risers much smaller than heretofore relatively to the casting proper. This is be cause required liquidity in the riser has been heretofore maintainable, sufiiciently long, only by. increasing its bulk very largely in excess of that required to fill the casting. It has thus been usually necessary, in casting with sand molds for example, to have the riser fully as bulky as the casting, and in casting some alloys, such as aluminum bronze, for example, the ratio of bulk of riser to that of casting has been as high as 1} to 1. But, by my method, these relative proportions of riser to casting are revolutionized, it being possible thereby to maintain, sufficiently liquid, a comparatively small riser (say, in usual practice, not to ex ceed one fourth the bulk of the casting), sufficiently long to supply sufficient molten metal to all cavities in the solidifying casting.

My method, including its employment of a my molds as hereinbefore described, I have found especially advantageous in casting copper, nickel, lead, zinc, aluminum, and many alloys comprising some of those metals such as German silver, brass, bronze, gunmetal and white metals, and it has proved also very useful in the casting of ferro-metals and their alloys.

What I claim as new and desire to secure .by Letters Patent is the following, viz

1. As a new article, a mold for metal,

or its alloys, composed principally of a nonmetallic rapidly heat-diffusing substance, and comprising, for the casting proper, a mold composed principally of graphitized carbon, in combination with a less rapidly heat-difiusing riser. 2. As a new article, a mold for metal, or its alloys, composed principally of a nonmetallic rapidly heat-diflusing substance, and comprising, for the casting proper, a mold composed principally of graphitized carbon, in combination with a riser member composed principally of sand.

3'. As a new article,a mold for metals, or their alloys, composed partly of graphitized carbon and partly of another substance.

1. As a new article, a mold for metals, or their alloys, comprising a mixture of graphitized carbo'n with another substance.

5. As a new article a mold for metals, or their alloys, comprising a mixture containing graphitized carbon and amorphous car- 6. A mold for metals or their alloys having the bottom and sides of its matrix composed of graphitized carbon in combination with a less rapidly-heat diffusing riser.

7. A mold for metals or their alloys having the bottom and sides of its matrix composed principally of graphitized carbon, and the major portion of the top of its matrix inclosed by less rapidly heat-diffusing matter.

8. A mold for metals or their alloys having the bottom and sides of its matrix composed of graphitized carbon, in combination with a less rapidly heat-diffusing riser.

9. A mold for metals, or their alloys, composed in'part of graphitized carbon, and in part of less rapidly heat-diffusing matter.

CHARLES VIGKERS.

Witnesses:

L. E. BARTON, J MGCALLUM. 

